Alarm Circuits
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FIG. 1 is a circuit diagram of it, it is in the audio circuit from the resistance between the two leads to a probe to rain alarm. Fig. 2 with CCL to make a probe connected to t.. -
Explanation Here is a simple fire alarm circuit based on an LDR fire detection sensor. Smoke generated during circuit generates an audible alarm, fire smoke in case of fire. Al.. -
Door alarm here with a time recognition, the owner opened the door is normally open the door, open the door to complete the action within the general 30s, so it does not alarm,.. -
Ding for the circuit principle: care, vs SCR trigger grounded, it is in the off state. When someone leads A burglar broke, the SCR trigger end to give a trigger voltage is turn.. -
The circuit generates a warble-tone alarm signal that simulates the sound of a British police siren. IC1 is wired as an alarm generator and IC2 is wired as a 1 Hz astable multivibrator. The output of IC2 is used to frequency modulate IC1 via R5... -
The single-chip, burglar -alarm circuit shown uses a dual 556 timer, draws 10 mA of standby current, and generates a pulsing alarm signal that conserves battery energy. Once activated, the alarm wilLremain on, independent of the subsequent state of any of.... -
False alarms produced by semiconductor failure are impossible with this burglar-alarm circuit equipped with relays. What"s more, the circuit is virtually immune to false triggering. With a standby current of less than 0.1 mA, the circuit offers all the.... -
The heart of the circuit is a 555 oscillator /timer, Ul, configured for monostable operation. The output of Ul at pin 3 is tied to the gate of SCRl. As long as Sl-S5, which are connected to the trigger input of Ul, are open, the circuit remains in the.... -
The tracer, consisting of both a transmitter and receiver, is designed to follow a closed-loop wire or cable system. It follows an induced voltage path created by feeding a low-current, audio-frequency signal through the cable. When the pick-up coils.... -
When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is ene.. -
This alarm circuit activates when SI through S5 are activated. This lights LED1 and activates Ql via IC1C and IC1D. RY.. -
This circuit uses a 556 to first generate a low frequency square wave, that is modulated to produce two alternate tones of about 400 and 500 Hz. Circuit generates warble alarm of European emergency vehicles. .. -
In the circuit, U1 amplifies the audio picked up by the condenser microphone. Resistor Rl limits current, while R2 and R3 center the output of the amplifier to %B+ to allow a single-ended supply to be used. Diodes D1 and D2 rectify the output of Ul, and C3.... -
The alarm uses a fixed-frequency piezoelectric buzzer in conjunction with the cadmium-sulfide (CDS) cell and the two-transistor circuit to provide a unique effect. Whenever light reaches the CDS photo-electric cell, the alarm is silent. But when no light.... -
The burglar chaser makes a great accessory for any alarm system. It creates brilliant flashes of white light and a loud, irritating sound from a metal horn buzzer. Transformer T1 is connected to Ql, Rl, and R2 to form a blocking oscillator. This creates a.... -
The baby-alert transmitter is built around an LM324 quad op amp (Ul), two LMC555CM CMOS oscillator/timers (U2 and U3), and a few support components. The transmitter sends a signal on receipt of a sound at MIC1... -
The baby-alert receiver is comprised of three transistors: Q2, which is configured as a high-gain linear amplifier; Q3, which serves as both an amplifier and detector; and Q4. which is essentially used as a switch; and a few additional components... -
This circuit is useful if you need a low-energy flashing alarm. The 200 to 400-dc supply should have enough internal resistance to charge the 0.5 capacitor between flashes, about 2 or 3 time constants, which means about 500 kQ to 1 for a 1-s rate. .. -
IC1 contains several oscillators and an amplifier. The low-frequency audio-signal oscillator is used to supply an input to the amplifier. That signal is the audio tone that is amplified, then supplied to the speaker by the amplifier. The high-frequency.... -
This circuit uses inexpensive, common components to generate a precise dial tone for phone applications (see the figure). Ul (an Intel 82C54 timer-counter) generates 350 and 440Hz square waves that are filtered by Rl/Cl and R,JC2, and mixed together by.... -
This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to.... -
This inexpensive dc supply-voltage monitor sounds a warning when the voltage falls below a preset value. It is ideal for monitoring rechargeable batteries since it draws only a few microamperes when not sounding. The voltage at which the alarm sounds is.... -
This circuit simulates the sound of an American police siren. IC2 is wired as a low frequency astable that has a cycling period of about 6 seconds. The slowly varying ramp waveform on Cl is fed to pnp emitter follower Ql, and is then used to frequency.... -
The circuit has two ranges: 10 sees to 5 mins and 1 min to 80 mins. It can be powered by a 9-V battery. With the LED connected as shown a reasonable frequency of flashing occurs throughout the range of operation. .. -
When this car alarm circuit is activated it stays activated for 80 seconds. It has 15 seconds delay for the driver to enter and deactivate. and All timmings can be altered easilly..... -
3-phase power, would endanger the electrical equipment (especially asynchronous motor) security, in order to detect phase failure, it can be made with a broken alarm. Circuit s.. -
Circuit works: QM-NJ9 is alcohol sensor. QM-NJ9 contact after the odor of alcohol, the resistance value A, B between the reduced.. -
The circuit has a built-in, self-arming feature. The driver turns off the ignition, presses the arm button on theComputalarm, and leaves the car. Within 20 seconds, the alarm arms itself—all automatically! The circuit will then detect the opening of any.... -
The circuit shown is the second natural gas (gas) stove flame alarm. After the gas stove ignited normal combustion, close the power switch S. Photoresistor RG due.. -
When the alarm protection can be higher or lower than the predetermined value in the mains voltage, sound and light alarm,.. -
Circuit operation principle of the device shown in Figure 13. When the barbed wire Fe intact, LSE's O, feet collusion between its pin output high,.. -
Circuit works: This is an AC blown fuse alarm. When BX is not when blown, 220 V AC voltage through a VD1 VD4 bridge rectifier, R1 limiting buck, after DW 6V DC..
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New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
Popular Circuits
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Differentiating circuit as shown for the utility. The op amp circuit constituted by Universal....